Jet noise suppressor nozzle



June 4, 1963 D. M. BROWN ETAL 3,092,205

JET NOISE SUPPRESSOR NOZZLE Filed Aug. 22, 1958 4 Sheets-Sheet 1 Inventors.- awu Mai-n3 aka/ 43 r /rcaz 6M 46%,

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vQw a/auza/ Attorneys June 4, 1963 D. M. BROWN ETAL 3,092,205

JET NOISE SUPPRESSOR NOZZLE Filed Aug. 22, 1958 4 Sheets-Sheet 2 am! @1746. 6 14mm Inventors A ftorneys June 4, 1963 Filed Aug. 22, 1958 D. M. BROWN ETAL 3,092,205

JET uoxss SUPPRESSOR NOZZLE 4 Sheets-Sheet 3 Attorneys June 4, 1963 D. M. BROWN ETAL JET NOISE SUPPRESSOR NOZZLE 4 Sheets-Sheet 4 Filed Aug. 22, 1958 F/GS.

nnnnnnn uuuuuu Attorneys United States atent 3,092,205 Fatenteci June 4, 1963 3,092,205 JET NOISE SUPPRESSOR NOZZLE David Morris Brown, Alvaston, Derby, John Michael Storer Keen, Allestree, and Bertram Harry Urmston, Kingsway, England, assignors to Rolls-Royce Limited, Derby, England, a company of Great Britain Filed Aug. 22, 1958, Ser. No. 756,659 Claims priority, application Great Britain Sept. 2, 1957 13 Claims. (Cl. 18141) This invention relates to a jet noise suppressor nozzle.

According to the invention there is provided a jet noise suppressor nozzle having a plurality of longitudinally extending, substantially radial hollow lobes for the flow therethrough of hot gases from a jet pipe, the lobes being angularly spaced from each other in a circular arrangement, each lobe increasing in radial extent in a downstream direction and having substantially radially-extending walls which are corrugated at least in part, the corrugations extending substantially longitudinally of the nozzle.

Each radially-extending wall is preferably corrugated symmetrically so as to form, in transverse section, successive part-cylindrical portion. The hoop stress in each said part-cylindrical portion is preferably taken by transverse discrete or continuous local ties or struts. The ties or struts may be secured to stiffeners extending longitudinally of the nozzle and the longitudinal stiffeners may be in short discrete portions or they may be in continuous lengths.

The nozzle may be provided adjacent its centre with means for bracing the various lobes to each other. Thus the said bracing means may comprise a lobulated frame each of whose lobules extends into and is secured to a lobe of the nozzle, the frame being disposed adjacent the centre of the nozzle. Preferably the frame has a portion extending outwardly of the downstream end of the nozzle.

Each lobe may be formed longitudinally so as to have a converging-diverging portion.

The lobes preferably extend to the downstream edge of the nozzle, but the corrugations in each radial wall preferably do not extend to the downstream edge of the nozzle.

The lobes can be double-s-kinned and the skins of each lobe can be internally braced. The outer skin preferably forms the nacelle fairing line.

The cross sectional width of each lobe preferably increases in a radially outward direction.

The invention is illustrated, merely by way of example, in the accompanying drawings, in which:

FIGURE 1 is a perspective view of a jet noise suppressor nozzle embodying the invention, part of the nozzle being broken away to show internal stiffeners;

FIGURE 2 is a longitudinal section through one of the lobes of the nozzle shown in FIGURE 1;

FIGURE 3 is a section on line 3-3 of FIGURE 2 showing the successive part-cylindrical portion configuration;

FIGURE 4 is a section on line 44 of FIGURE 2;

FIGURE 5 is a diagrammatic side elevation of a gas turbine engine embodying the nozzle shown in FIGURES FIGURE 6 is a perspective view of a second, and preferred embodiment of a jet noise suppressor nozzle according to the invention;

FIGURE 7 is a longitudinal section through one of the lobes of the nozzle shown in FIGURE 6;

FIGURES 8-10 are sections on the lines 88, 9-9, and 1010 respectively of FIGURE 7;

FIGURE 11 is a section on the line 11--11 of FIG- URE 10, and

FIGURE 12 is a diagrammatic side elevation of a gas turbine engine embodying the nozzle shown in FIG- URES 6-1l.

The same reference numerals are used throughout the various views for similar parts.

Referring first to the embodiment illustrated in FIG- URES l-S, a jet noise suppressor nozzle 10 has a plurality of longitudinally extending, substantially radial, hollow lobes 8 for the flow therethrough of the hot gases from a jet pipe, the direction of gas flow being indicated by the arrow 9. The lobes '8 are angularly spaced apart from each other in a circular arrangement and extend to the downstream edge of the nozzle. Each lobe 8 increases in radial extent in a downstream direction, the crosssectional width of each lobe 8 increasing in a radially outward direction.

Each lobe 8 has radially-extending walls 8', 8" connected together at their outer peripheral ends, the walls being formed of an external skin 11 and an internal skin 12, see FIGURE 2. The internal skin 12 provides a passage for the hot gases.

The two radially-extending walls of the internal skin 12 are corrugated symmetrically (as best seen in FIG- URES 3 and 4) and the corrugations 14, which extend substantially longitudinally of the nozzle but which do not extend to the downstream edge thereof, form, in transverse section, successive part-cylindrical portions.

The hoop stress in each said part-cylindrical portion is taken by longitudinal stiffeners such as 16 (FIGURE 4) and by discrete transverse, local ties or struts 13. The struts 13 are of aerofoil section and are inclined to follow generally the direction of gas flow.

The inner skin 12 of the double skinned walls is braced by struts 15 attached to the longitudinal stiifeners 16 and arranged so that in conjunction with adjacent aerofoil struts 13 they form, effectively, continuous ties.

If desired, additional longitudinal stiffeners may be attached to the internal skin 12 of each lobe 3.

The nozzle It) can be attached, for example, to the downstream end of a gas turbine engine 17, as shown in FIGURE 5, and the gases emitted from the jet pipe will flow internally of the skin 12 and Within the corrugations 14.

Referring now to the preferred embodiment of the invention illustrated in FIGURES 6-l2, this is generally similar to the embodiment of FIGURES 1-5 for which reason it will not be described in detail. In the said preferred embodiment, however, a lobulated frame 20 is disposed internally of the downstream end of the nozzle adjacent the centre thereof and has a plurality of lobules 21 each of which extends into and is secured to a lobe 8 of the nozzle. The frame 20 thus serves to brace the lobes 8 to each other and makes for a stronger construction than that of FIGURES l-S. The frame 29 has, moreover, a portion 22 which extends outwardly of the downstream end of the nozzle.

The form of the corrugations 14 of the preferred embodiment will be readily apparent from a comparison of FIGURES 8-10 and it will be seen from FIGURE 10 that the corrugations 14 do not extend to the downstream edge of the nozzle. The hoop stress in each part-cylindrical portion is taken by substantially I-shaped members 23 (see also FIGURES 6 and 7) which are continuous members (as opposed to the discrete struts 13) and which extend longitudinally substantially throughout the length of the lobes 8.

Each lobe 8 in the preferred embodiment (see FIGURE 7) is for-med longitudinally so as to have a convergingdiverging portion disposed adjacent the downstream end of the nozzle, the throat 24 of this converging-diverging portion being disposed adjacent the section line 8-8.

FIGURE 11 shows how the desired variation in the crosssectional area of the nozzle is achieved by shaping the internal skin 12 of each lobe 8. The cross-sectional area of each lobe remains substantially constant at first, i.e., adjacent its upstream end, and is then reduced to the throat 24 after which it is increased again to the outlet 25, thus providing the desired convergingdiverging shape.

The jet noise suppressor nozzles shown in FIGURES 15 and 612 have the advantage over conventional nozzles of providing a rigid, though light, structure in which the propulsive losses due to turbulence are reduced. The lobes are divided by the successive part-cylindrical portions into a number of passages for the how of hot gases, which passages are very approximately circular in section and hence well adapted for non-turbulent gas =ilow therethrough.

We claim:

1. A jet noise suppressor nozzle having a plurality of longitudinally extending, substantially radial, hollow lobes for the flow therethrough of hot gases from a jet pipe, the lobes being angularly spaced from each other in a circular arrangement, each lobe increasing in radial extent in a downstream direction from a communicating central area and having substantially radially-extending walls which are corrugated at least in part, the corrugations extending substantially longitudinally of the nozzle, and a lobulated frame each of whose lobules extends into and is secured to a lobe of the nozzle, the frame being disposed adjacent the centre of the nozzle.

2. A jet noise suppressor nozzle as claimed in claim 1 in which the frame has a portion extending outwardly of the downstream end of the nozzle.

3. A jet noise suppressor nozzle having a plurality of longitudinally extending, substantially radial, hollow lobes for the flow therethrough of hot gases from a jet pipe, the lobes being angularly spaced from each other in a circular arrangement, each lobe increasing in radial extent in a downstream direction from a communicating central area and having double-skinned substantially radiallyextending walls whose inner skin follows the general configuration of the outer but is corrugated at least in part, the corrugations extending substantially longitudinally of the nozzle.

4. A jet noise suppressor nozzle as claimed in claim 3 in which the inner skins of the double skinned walls are internally braced.

5. A jet noise suppressor nozzle as claimed in claim 3 in which the cross sectional width of each lobe increases in a radially outward direction.

6. A jet noise suppressor nozzle having a plurality of longitudinally extending, substantially radial, hollow, circumferentially spaced apart lobes for the how therethrough of hot gases from a jet pipe, the lobes being angularly spaced from each other in a circular arrangement, each lobe increasing in radial extent in a downstream direction from a communicating central area and having substantially radially-extending spaced walls which are symmetrically corrugated on opposite sides thereof, the corrugations extending substantially longitudinally of the nozzle and providing the lobe, in transverse section with radially successive part-cylindrical portions to add rigidity thereto and to increase silencing by increasing the length of periph ral contact between the hot gases and the atmospheric air flowing between the spaced lobes.

7. The jet noise suppressor nozzle as defined in claim 6 in which there are transverse local ties attached to said radially extending walls at the junctions between said part-cylindrical portions and serving to take the hoop stress in each said part-cylindrical portions.

8. The jet noise suppressor nozzle as defined in claim 7 in which the said corrugations increase progressively in length from the central area outwardly and in which each junction between corrugations is reinforced by a stilfener, said ties being connected to the stifieners to stabilize the nozzle structure.

9. A jet noise suppressor nozzle having a plurality of longitudinally extending, substantially radial, hollow lobes for the flow therethrough of hot gases from a jet pipe, the lobes being angularly spaced from each other in a circular arrangement, each lobe increasing in radial extent in a downstream direction from a communicating central area and having spaced, substantially radially-extending walls which are symmetrically corrugated on opposite sides thereof, the corrugations extending substantially longitudinally of the nozzle, increasing in length and width outwardly from the central area and providing the lobe, in transverse section with successive, closely radially spaced, part-cylindrical portions, transverse local ties, attached to said walls between said part-cylindrical portions and serving to take the hoop stress in each said part-cylindrical portion and stifieners each secured to several of said ties and extending longitudinally of the nozzle.

10. A jet noise suppressor nozzle having a plurality of longitudinally extending, substantially radial, hollow, circumferentially spaced apart lobes for the flow therethrough of hot gases from a jet pipe, the lobes being formed with fixed converging-diverging portions and being angularly spaced from each other in a circular arrangement, each lobe increasing in radial extent in a downstream direction and having substantially radially-extending walls which are symmetrically and oppositely corrugated, the corrugations extending substantially longitudinally of the nozzle and opposing ones forming part cylindrical channels in each lobe.

11. A jet noise suppressor nozzle having a plurality of longitudinally extending, substantially radial, hollow, circumferentially spaced apart lobes for the llow therethrough of hot gases from a jet pipe, the lobes being angularly spaced from each other in a circular arrangement, each lobe increasing in radial extent in a downstream direction and having substantially radially-extending, circumferentially spaced walls symmetrically and oppositely corrugated at least in part, the corrugations extending substantially longitudinally of the nozzle whereby opposing channels thereof form part-cylindrical and radially connected passages in each lobe.

12. A jet noise suppressor nozzle as claimed in claim 10 in which the converging-diverging portions are disposed adjacent the downstream end of the nozzle.

13. A jet suppressor nozzle as claimed in claim 10 in which the corrugations terminate upstream of the downstream edge of the nozzle.

References Cited in the file of this patent UNITED STATES PATENTS OTHER REFERENCES Publication: Journal of the Helicopter Association of Great Britain, pages 404-413, January 1956.

Publication: Aviation Age, pages 4853, April 1956. 

1. A JET NOISE SUPPRESSOR NOZZLE HAVING A PLURALITY OF LONGITUDINALLY EXTENDING, SUBSTANTIALLY RADIAL, HOLLOW LOBES FOR THE FLOW THERETHROUGH OF HOT GASES FROM A JET PIPE, THE LOBES BEING ANGULARLY SPACED FROM EACH OTHER IN A CIRCULAR ARRANGEMENT, EACH LOBE INCREASING IN RADIAL EXTENT IN A DOWNSTREAM DIRECTION FROM A COMMUNICATING CENTRAL AREA AND HAVING SUBSTANTIALLY RADIALLY-EXTENDING WALLS WHICH ARE CORRUGATED AT LEAST IN PART, THE CORRUGATIONS EXTENDING SUBSTANTIALLY LONGITUDINALLY OF THE NOZZLE, AND A LOBULATED FRAME EACH OF WHOSE LOBULES EXTENDS INTO AND IS SECURED TO A LOBE OF THE NOZZLE, THE FRAME BEING DISPOSED ADJACENT THE CENTRE OF THE NOZZLE. 